Hi Jia,
On 13/12/17 07:00, Jia He wrote:
> In our Armv8a server (qualcomm Amberwing, non VHE), after applying
> Christoffer's timer optimizing patchset(Optimize arch timer register
> handling), the guest is hang during kernel booting.
>
> The error root cause might be as follows:
> 1. in kvm_arch_timer_handler, it reset vtimer->cnt_ctl with current
> cntv_ctl register value. And then it missed some cases to update timer's
> irq (irq.level) when kvm_timer_irq_can_fire() is false
> 2. It causes kvm_vcpu_check_block return 0 instead of -EINTR
> kvm_vcpu_check_block
> kvm_cpu_has_pending_timer
> kvm_timer_is_pending
> kvm_timer_should_fire
> 3. Thus, the kvm hyp code can not break the loop in kvm_vcpu_block (halt
> poll process) and the guest is hang forever
>
> Fixes: b103cc3f10c0 ("KVM: arm/arm64: Avoid timer save/restore in vcpu entry/exit")
> Signed-off-by: Jia He <jia.he@xxxxxxxxxxxxxxxx>
> ---
> virt/kvm/arm/arch_timer.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
> index f9555b1..bb86433 100644
> --- a/virt/kvm/arm/arch_timer.c
> +++ b/virt/kvm/arm/arch_timer.c
> @@ -100,7 +100,6 @@ static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
> vtimer = vcpu_vtimer(vcpu);
>
> if (!vtimer->irq.level) {
> - vtimer->cnt_ctl = read_sysreg_el0(cntv_ctl);
> if (kvm_timer_irq_can_fire(vtimer))
> kvm_timer_update_irq(vcpu, true, vtimer);
> }
>
Which patches are you looking at? The current code in mainline looks
like this:
vtimer = vcpu_vtimer(vcpu);
vtimer->cnt_ctl = read_sysreg_el0(cntv_ctl);
if (kvm_timer_irq_can_fire(vtimer))
kvm_timer_update_irq(vcpu, true, vtimer);
I'd suggest you use mainline and report if this doesn't work.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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